Abstract
The present investigation was undertaken to understand the involvement of pineal in reproductive activities of the domestic pigeon, Columba livia. Activities of 17β, 3β and 3α-hydroxysteroid dehydrogenases were studied histochemically in the testis and ovary of normal and pinealectomised domestic pigeons during breeding (March, April and May) and nonbreeding seasons (June, July and August). Both the testis and ovary showed high activities of these enzymes during the breeding season as compared to the nonbreeding season in normal intact birds. Pinealectomy caused shrinkage of gonads during the breeding season and enlargement of gonads during the nonbreeding season. During the breeding season, pinealectomised birds showed low activities of all the enzymes which is well corroborated with the observed inactive shrunken condition of gonads. Increased activity of the steroid dehydrogenases during the non-breeding season in pinealectomised birds is indicative of the activation of gonads, which is well reflected by the observed enlargement of gonads. Apparently, the present results indicate that during the breeding season, pineal has a progonadal role while during the nonbreeding season it is antigonadal.
